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    <title>clCreateContext</title>
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    <div class="refentry">
      <a id="id-1"></a>
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      <div xmlns="" class="refnamediv">
        <a xmlns="http://www.w3.org/1999/xhtml" id="clCreateContext"></a>
        <h1>clCreateContext</h1>
        <p>Creates an OpenCL context.</p>
      </div>
      <div class="refsynopsisdiv">
        <h2></h2>
        <div class="funcsynopsis">
          <table xmlns="" border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
            <tr valign="bottom">
              <td>
                <code xmlns="http://www.w3.org/1999/xhtml" class="funcdef"><a class="link" href="abstractDataTypes.html" target="_top">cl_context</a> <strong class="fsfunc">clCreateContext</strong>(</code>
                <td>const <a xmlns="http://www.w3.org/1999/xhtml" class="link" href="enums.html#cl_context_properties" target="_top">cl_context_properties</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*properties</var>, </td>
              </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="_top">cl_uint</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">num_devices</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>const <a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="_top">cl_device_id</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*devices</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="_top">(void</a>CL_CALLBACK  <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*pfn_notify)</var> 
                        <code xmlns="http://www.w3.org/1999/xhtml">(</code><div xmlns="http://www.w3.org/1999/xhtml" class="literallayout"><p>const <a class="link" href="scalarDataTypes.html" target="_top">char</a> *errinfo, <br />
                        const <a class="link" href="scalarDataTypes.html" target="_top">void</a> *private_info, <a class="link" href="otherDataTypes.html" target="_top">size_t</a> cb, <br />
                        <a class="link" href="scalarDataTypes.html" target="_top">void</a> *user_data</p></div><code xmlns="http://www.w3.org/1999/xhtml">)</code>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="_top">void</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*user_data</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td><a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="_top">cl_int</a> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*errcode_ret</var><code>)</code></td>
            </tr>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
            An OpenCL context is created with one or more devices. Contexts
are used by the OpenCL runtime for managing objects such as command-queues, memory,
program and kernel objects and for executing kernels on one or more devices specified in the
context.
        </p>
      </div>
      <div class="refsect1">
        <a id="parameters"></a>
        <h2>Parameters</h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">properties</span>
            </dt>
            <dd>
              <p>
                    Specifies a list of context property names and their corresponding values. Each property name is 
                    immediately followed by the corresponding desired value. The list is terminated with 0. 
                    <code class="varname">properties</code> can be NULL in which case the platform that is selected is 
                    implementation-defined. The list of supported <code class="varname">properties</code> is described in the table below. 
                </p>
              <p>
                    If the extension <a class="citerefentry" href="cl_khr_d3d10_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_d3d10_sharing</span></span></a>
                    is enabled, then if a property is not specified in <code class="varname">properties</code>, then its default value is used
                    (it is said to be specified implicitly). If <code class="varname">properties</code> is NULL or empty (points to a list 
                    whose first value is zero), all attributes take on their default value.
                </p>
              <p>
                    If the extension <a class="citerefentry" href="cl_khr_gl_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_sharing</span></span></a>
                    is enabled, then <code class="varname">properties</code> points to an attribute list, which is a array of ordered &lt;attribute name, value&gt; pairs terminated with zero. If an attribute is not specified in <code class="varname">properties</code>, then its default value is used (it is said to be specified implicitly). If <code class="varname">properties</code> is NULL or empty (points to a list whose first value is zero), all attributes take on their default values..
                </p>
              <div class="informaltable">
                <table border="1">
                  <colgroup>
                    <col align="left" class="col1" />
                    <col align="left" class="col2" />
                    <col align="left" class="col3" />
                  </colgroup>
                  <thead>
                    <tr>
                      <th align="left">cl_context_properties enum</th>
                      <th align="left">Property value</th>
                      <th align="left">Description</th>
                    </tr>
                  </thead>
                  <tbody>
                    <tr>
                      <td align="left">
                        <code class="constant">CL_CONTEXT_PLATFORM</code>
                      </td>
                      <td align="left">
                        <a class="link" href="abstractDataTypes.html" target="_top">cl_platform_id</a>
                      </td>
                      <td align="left">Specifies the platform to use.</td>
                    </tr>
                    <tr>
                      <td align="left">
                        <code class="constant">CL_CONTEXT_D3D10_DEVICE_KHR</code>
                      </td>
                      <td align="left">ID3D10Device*</td>
                      <td align="left">If the <a class="citerefentry" href="cl_khr_d3d10_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_d3d10_sharing</span></span></a> 
            extension is enabled, specifies the ID3D10Device* to use for Direct3D 10 interoperability. The default value is NULL.</td>
                    </tr>
                    <tr>
                      <td align="left">
<div class="literallayout"><p><code class="constant">CL_GL_CONTEXT_KHR</code><br />
<code class="constant">CL_EGL_DISPLAY_KHR</code><br />
<code class="constant">CL_GLX_DISPLAY_KHR</code><br />
<code class="constant">CL_WGL_HDC_KHR</code><br />
<code class="constant">CL_CGL_SHAREGROUP_KHR</code></p></div></td>
                      <td align="left"> </td>
                      <td align="left">Available if the <a class="citerefentry" href="cl_khr_gl_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_sharing</span></span></a> 
            extension is enabled.</td>
                    </tr>
                  </tbody>
                </table>
              </div>
            </dd>
            <dt>
              <span class="term">
                <code class="varname">num_devices</code>
              </span>
            </dt>
            <dd>
              <p>
                    The number of devices specified in the <code class="varname">devices</code> argument.
                </p>
            </dd>
            <dt>
              <span class="term">
                <code class="varname">devices</code>
              </span>
            </dt>
            <dd>
              <p>
                    A pointer to a list of unique devices returned by <a class="citerefentry" href="clGetDeviceIDs.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceIDs</span></span></a> 
                    for a platform. Duplicate devices specified in <code class="varname">devices</code> are ignored.
                </p>
            </dd>
            <dt>
              <span class="term">
                <code class="varname">pfn_notify</code>
              </span>
            </dt>
            <dd>
              <p>
                    A callback function that can be registered by the application. This callback function will be used by the OpenCL implementation to report information on errors that occur in this context. This callback function may be called asynchronously by the OpenCL implementation.
It is the application's responsibility to ensure that the callback function is thread-safe. If <code class="varname">pfn_notify</code> is NULL, no callback function is registered. The parameters to this callback function are:
                </p>
              <p><code class="varname">errinfo</code> is a pointer to an error string.</p>
              <p><code class="varname">private_info</code> and <code class="varname">cb</code> represent a pointer to binary data that is returned by the OpenCL implementation that can be used to log additional information helpful in debugging the error.</p>
              <p><code class="varname">user_data</code> is a pointer to user supplied data.</p>
              <p>NOTE: There are a number of cases where error notifications need to be delivered due to an error that occurs outside a context. Such notifications may not be delivered through the <code class="varname">pfn_notify</code> callback. Where these notifications go is implementation-defined.</p>
            </dd>
            <dt>
              <span class="term">
                <code class="varname">user_data</code>
              </span>
            </dt>
            <dd>
              <p>
                    Passed as the <code class="varname">user_data</code> argument when <code class="varname">pfn_notify</code> is called. <code class="varname">user_data</code> can be NULL.
                </p>
            </dd>
            <dt>
              <span class="term">
                <code class="varname">errcode_ret</code>
              </span>
            </dt>
            <dd>
              <p>
                    Returns an appropriate error code. If <code class="varname">errcode_ret</code> is NULL, no error code is returned.
                </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1">
        <a id="notes"></a>
        <h2>Notes</h2>
        <p>
            <code class="function">clCreateContext</code> and <a class="citerefentry" href="clCreateContextFromType.html"><span class="citerefentry"><span class="refentrytitle">clCreateContextFromType</span></span></a> perform an implicit retain. This is very helpful for 3rd party libraries, which typically get a context passed to them by the application.
However, it is possible that the application may delete the context without informing the library.
Allowing functions to attach to (i.e. retain) and release a context solves the problem of a context
being used by a library no longer being valid.
        </p>
      </div>
      <div class="refsect1">
        <a id="errors"></a>
        <h2>Errors</h2>
        <p><code class="function">clCreateContext</code> returns a valid non-zero context and <code class="varname">errcode_ret</code> is set to <span class="errorname">CL_SUCCESS</span> if the context is created  successfully. Otherwise, it returns NULL value with the following error
values returned in <code class="varname">errcode_ret</code>:
</p>
        <div class="itemizedlist">
          <ul class="itemizedlist" style="list-style-type: disc; ">
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_PLATFORM</span> if <code class="varname">properties</code> is NULL and no platform could be selected or if platform value specified in <code class="varname">properties</code> is not a valid platform. (If the extension <a class="citerefentry" href="cl_khr_gl_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_sharing</span></span></a> is enabled, then see error "CL_INVALID_GL_SHAREGROUP_REFERENCE_KHR" below.)
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_PROPERTY</span> if context property name in <code class="varname">properties</code> is not a supported
            property name, if the value specified for a supported property name is not valid, or if the
            same property name is specified more than once. However if the extension <a class="citerefentry" href="cl_khr_gl_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_sharing</span></span></a> is enabled, then CL_INVALID_PROPERTY is returned if an attribute name other than those listed in the table for <code class="varname">properties</code> above is specified in <code class="varname">properties</code>.
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_VALUE</span> if <code class="varname">devices</code> is NULL; if <code class="varname">num_devices</code> is equal to zero; or 
            if <code class="varname">pfn_notify</code> is NULL but <code class="varname">user_data</code> is not NULL.
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_DEVICE</span> if <code class="varname">devices</code> contains an invalid device.
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_OPERATION</span> if Direct3D 10 interoperability is specified by setting CL_INVALID_D3D10_DEVICE_KHR 
            to a non-NULL value, and interoperability with another graphics API is also specified (if the 
            <a class="citerefentry" href="cl_khr_d3d10_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_d3d10_sharing</span></span></a> extension is enabled).
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_DEVICE_NOT_AVAILABLE</span> if a device in <code class="varname">devices</code> is currently not available 
            even though the device was returned by <a class="citerefentry" href="clGetDeviceIDs.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceIDs</span></span></a>.
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_OUT_OF_RESOURCES</span> if there is a failure to allocate resources required by the OpenCL 
            implementation on the device.
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_OUT_OF_HOST_MEMORY</span> if there is a failure to allocate resources required by the OpenCL 
            implementation on the host.
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_D3D10_DEVICE_KHR</span> if the Direct3D 10 device specified for interoperability is not 
            compatible with the devices against which the context is to be created (if the 
            <a class="citerefentry" href="cl_khr_d3d10_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_d3d10_sharing</span></span></a> extension is enabled).
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_D3D10_DEVICE_KHR</span> if the value of the property CL_CONTEXT_D3D10_DEVICE_KHR is non-NULL 
            and does not specify a valid Direct3D 10 device with which the <code class="varname">cl_device_ids</code> against which this context 
            is to be created may interoperate (if the 
            <a class="citerefentry" href="cl_khr_d3d10_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_d3d10_sharing</span></span></a> extension is enabled).
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_GL_SHAREGROUP_REFERENCE_KHR</span> when an invalid OpenGL context or share group 
                object handle is specified in <code class="varname">properties</code> (only if the
            <a class="citerefentry" href="cl_khr_gl_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_sharing</span></span></a> extension is enabled).
        </li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_GL_SHAREGROUP_REFERENCE_KHR</span> if the
            <a class="citerefentry" href="cl_khr_gl_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_sharing</span></span></a> extension is enabled and if a context was specified by any of the following means:
                <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem" style="list-style-type: disc">
                        Context specified for an EGL-based OpenGL ES or OpenGL implementation by 
                        setting the attributes CL_GL_CONTEXT_KHR and CL_EGL_DISPLAY_KHR. 
                    </li><li class="listitem" style="list-style-type: disc">
                        Context was specified for a GLX-based OpenGL implementation by setting the 
                        attributes CL_GL_CONTEXT_KHR and CL_GLX_DISPLAY_KHR.
                    </li><li class="listitem" style="list-style-type: disc">
                        Context was specified for a WGL-based OpenGL implementation by setting the 
                        attributes CL_GL_CONTEXT_KHR and CL_WGL_HDC_KHR.
                    </li></ul></div>
            and any of the following conditions hold:
                <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem" style="list-style-type: disc">
                        The specified display and context attributes do not identify a valid OpenGL or 
                        OpenGL ES context.
                    </li><li class="listitem" style="list-style-type: disc">  
                        The specified context does not support buffer and renderbuffer objects.
                    </li><li class="listitem" style="list-style-type: disc">      
                        The specified context is not compatible with the OpenCL context being 
                        created (for example, it exists in a physically distinct address space, 
                        such as another hardware device, or does not support sharing data with OpenCL 
                        due to implementation restrictions).
                    </li></ul></div></li>
            <li class="listitem" style="list-style-type: disc"><span class="errorname">CL_INVALID_GL_SHAREGROUP_REFERENCE_KHR</span> if a share group was specified 
            for a CGL-based OpenGL implementation by setting the attribute CL_CGL_SHAREGROUP_KHR, and the 
            specified share group does not identify a valid CGL share group object (only if the
            <a class="citerefentry" href="cl_khr_gl_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_sharing</span></span></a> extension is enabled).
        </li>
          </ul>
        </div>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p><img src="pdficon_small1.gif" />
            <a href="http://www.khronos.org/registry/cl/specs/opencl-1.1.pdf#page=45" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
<a class="citerefentry" href="clGetDeviceIDs.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceIDs</span></span></a>, <a class="citerefentry" href="clCreateContextFromType.html"><span class="citerefentry"><span class="refentrytitle">clCreateContextFromType</span></span></a>,  <a class="citerefentry" href="clRetainContext.html"><span class="citerefentry"><span class="refentrytitle">clRetainContext</span></span></a>,  <a class="citerefentry" href="clReleaseContext.html"><span class="citerefentry"><span class="refentrytitle">clReleaseContext</span></span></a>,   
<a class="citerefentry" href="clGetContextInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetContextInfo</span></span></a>,
            <a class="citerefentry" href="classDiagram.html"><span class="citerefentry"><span class="refentrytitle">Cardinality Diagram</span></span></a>
        </p>
      </div>
      <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4>
            Copyright © 
    Copyright © 2007-2010 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
permit persons to whom the Materials are furnished to do so, subject to
the condition that this copyright notice and permission notice shall be included
in all copies or substantial portions of the Materials.
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